Henning wrote: Boron actually is one of the hardest materials. Ok, hardness might be not the only thing to prevent electrode degradation.
In some configurations it even outperforms diamond:
http://www.newscientist.com/article/mg20327241.200-diamonds-are-for-softies–boron-is-harder.html?full=true&print=true
As pure boron (B28), which is half as hard as diamond (see above), it looks like this:
http://www.ethlife.ethz.ch/archive_articles/090129_Oganov_Bor/index_EN
Might be still hard to produce anyway.
You threw me a bit with that. B28? That would be, let’s see, 5 protons and 23 neutrons? Nah. But a crystal of 28 boron atoms: that’s quite a rig! On the downside, making boron a machine-tool resource would make it more valuable/costly. Oh, well.